in reply to You can do string interpolation on sub output
in thread What's the Right Way to declare constants in packages?

Note that you are far better off breaking out of the string instead of interpolating in this fashion, because Perl has to put your subroutine's output into an array reference, de-reference it, then string-ify it. It's far more efficient to do this:
my $str = "I like ... I like " . pi;